The long-term objective is to study the functional properties of human hemoglobins that have been altered by mutation, chemical modification, or both in order to gain further insight into the molecular mechanisms involved in the binding and transport of oxygen by hemoglobin. The results will be used for two purposes. First, attempts will be made to correlate functional properties with structural alterations in order to better understand the contributions of specific amino acid residues in hemoglobin and changes in the molecule's tertiary and quaternary structures to its oxygen transport. Second, functional properties of chemically modified hemoglobins will be measured and analyzed in an attempt to identify and design cross-linking reagents that may be useful in producing hemoglobin-based substitutes for whole blood transfusion. The specific aims include: (1) The functional properties of chemically cross-linked normal and mutant hemoglobins will be measured and correlated in order to identify structural modifications that result in oxygen binding properties that are in a physiologically useful range when the modified hemoglobin is free in solution. (2) Functionally abnormal hemoglobins will be examined in detail to determine, as precisely as possible, which parts of the overall reaction with oxygen have been altered by the mutational change. (3) Previously unstudied and all new abnormal hemoglobins that can be obtained will be screened for their general parameters of oxygen binding in order to identify whether or not the altered residue influences normal oxygen binding. (4) Attempts will be made to correlate changes in oxygen equilibrium reaction with altered protein structure in order to better understand the normal reaction mechanism and the relation of the structure and function of this protein. The principal methods used will be the measurement of oxygen equilibrium reaction over its full range by the automatic recording method under various controlled conditions of pH, ions, and temperature.